Could widespread moisture-fueled fungus ruin fall colors in Colorado?

Aspen leaves litter a trail off Independence Pass in the fall of 2016. Colorado's vibrant autumn display is now only days away. Photo Credit: Jerilee Bennett, The Gazette

BY Seth Boster

September 3, 2019

A couple of weeks before the end of August last year, the pictures spread across social media, igniting shock and awe across Colorado.

Aspen trees were already glowing. Ready or not, leaf peepers sprang into action, embarking on trips typically reserved for September. A drought-stricken year had jump-started the phase: without moisture, green-inducing chlorophyll departed leaves early, turning gold on their way to shedding.

For 2019, Mother Nature has made more time for her admirers.

All around the state, onlookers anticipate the gilded age in the coming weeks. Of course, none has a crystal ball, Dan West among them, the Colorado State Forest Service point person basing predictions on helicopter flights over the mountains.

“But from the outlook,” he says, “it looks like we’re kinda set up perfect.”

A historically snowy winter and spring provided the moisture. Summer sunshine has been “adequate,” West says.

“We’ve had ideal conditions for growing. Now it’s just a matter of, do we get those perfect sunny days with cool nights to give us that show that we all want?”

Sudden frost could compromise the trick, observers know. And the vibrant outlook comes with another asterisk.

“Yay for moisture, but also fungus loves moisture,” says Carolina Manriquez, the state forester based in Steamboat Springs. “There’s been a little bit of an explosion of that in several areas.”

As aspens grow strong so do pathogens that latch onto leaves, browning them and spotting them black, dulling the display. Outbreaks happen in years like these: wet springs followed by dry summers.

If the attack is detected early enough, trees might flush their decaying coat and regenerate in time for an autumn shimmer. For others, the response is too late.

Victims are common to northwest Colorado as well as the state’s spectacular southwest corner, West says. But while Manriquez has seen the malady along some of Routt County’s popular viewing roads, she doesn’t expect a widespread impact.

“There’s still so much to see,” she says.

Which is also what West tells concerned travelers. “Not every stand or every drainage is affected in the state by any means,” he says. “There are just some areas more affected than others.”

More notable to Mark Loveall in Durango is the area’s recent dry spell — harsh enough for forecasters in August to warn of a return to drought conditions. The supervisor at the State Forest Service’s field office wonders if lower groves are on the verge of turning. “I really don’t know when the peak will be,” Loveall says.

He calls it another “roller coaster year” of weather. To West, the stark changes represent a changing climate.

“As opposed to decades past where we might’ve had a really wet several years or a really dry several years, the outlook appears as though we’re gonna see far more variability and timing, both precipitation-wise and temperature-wise, than we’ve ever had.”

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